Algorithmic Analysis of Chemical Dynamics of the Autoignition of NH 3 –H 2 O 2 /Air Mixtures
Ahmed T. Khalil,
Dimitris M. Manias,
Efstathios-Al. Tingas,
Dimitrios C. Kyritsis and
Dimitris A. Goussis
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Ahmed T. Khalil: Department of Mechanical Engineering, Khalifa University of Science and Technology, Abu Dhabi 127788, UAE
Dimitris M. Manias: Department of Mechanics, School of Applied Mathematics and Physical Sciences, National Technical University of Athens, 157 73 Athens, Greece
Efstathios-Al. Tingas: Perth College, University of the Highlands and Islands, (UHI), Perth PH1 2NX, UK
Dimitrios C. Kyritsis: Department of Mechanical Engineering, Khalifa University of Science and Technology, Abu Dhabi 127788, UAE
Dimitris A. Goussis: Department of Mechanical Engineering, Khalifa University of Science and Technology, Abu Dhabi 127788, UAE
Energies, 2019, vol. 12, issue 23, 1-14
Abstract:
The dynamics of a homogeneous adiabatic autoignition of an ammonia/air mixture at constant volume was studied, using the algorithmic tools of Computational Singular Perturbation. Since ammonia combustion is characterized by both unrealistically long ignition delays and elevated NO x emissions, the time frame of action of the modes that are responsible for ignition was analyzed by calculating the developing time scales throughout the process and by studying their possible relation to NO x emissions. The reactions that support or oppose the explosive time scale were identified, along with the variables that are related the most to the dynamics that drive the system to an explosion. It is shown that reaction H 2 O 2 (+M) → OH + OH (+M) is the one contributing the most to the time scale that characterizes ignition and that its reactant H 2 O 2 is the species related the most to this time scale. These findings suggested that addition of H 2 O 2 in the initial mixture will influence strongly the evolution of the process. It was shown that ignition of pure ammonia advanced as a slow thermal explosion with very limited chemical runaway. The ignition delay could be reduced by more than two orders of magnitude through H 2 O 2 addition, which causes only a minor increase in NO x emissions.
Keywords: explosive time scales; computational singular perturbation; autoignition; ammonia; additives; hydrogen peroxide; ignition delay control; NO x (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
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Persistent link: https://EconPapers.repec.org/RePEc:gam:jeners:v:12:y:2019:i:23:p:4422-:d:289367
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